speargun - shaft speed test

[ericd]

where can i get shaft speed tests for spearguns???

[richhermes]

You hold a radar gun and I'll shoot some at ya!!

HAHAHA

(Actually, do a search on here, Hector posted a link to some guy that did band tests and I think he had speeds on there)

[fernandezh]

http://www.spearboard.com/showthread.php?s=&threadid=1184

Eric,
Check out the above thread, and there is a link there to some guy who took speargun power testing and turned it into rocket science. He goes into more detail on how to do it than anybody I know. I prefer the Kiss (Keep it simple and stupid) method. If I think my bands are getting weak and I am not shooting as far as I used to, I change to new bands. I would rather spend my spare time either in the water spearing fish or on land looking to spear the elusive two legged ladyfish. Shalom!!

Hector.

[KJNDIVER]

I know in archery shops they have a device that measures arrow speed in fps. Electronic device with two large hoops or rings that the arrow is fired thru, measures time differntial when arrow passes from 1st loop to 2nd. Surely somewhere, someone has made adjustments for use underwater with spear guns. Unless you feel like firing your gun out of water.

[IyaDiver]

The machine KJN is talking about is a ballistic chronograph. I used to have that for my airgun testing but now it went bad.

With good modification, someone might be able to modify those speed sensors (light switch actually ) to be used underwater, but maybe hell of a job. I thought about it once though. I even thought about using a radar gun but sea water absorb alot of those wavelength,so they said. Radar gun must be used by the reader at an angle where the shaft is leaving the gun, it is not good to read at side angle, that's what the instruction said for baseball or any sport user.

If anyone wants to know how effective a rubber combination against a shaft mass/diameter the cheapest way I see without fancy equipment will be the ballistic putty penetration test. In the end what we want to measure is actually the power of the penetration of the speartip and shaft in a given target. Higher speed does give more momentum and so is heavier shaft if can be driven at "X" speed.


Eric,
Try to use ur search engine and find Oehler Chronograph. You can get a US$400 model and use it for ur speargun, but you must fire on land. Oehler has the biggest shooting window (sensor ) area which allows you to have some aiming error. Or try the Bushnell Sport Radar gun which I thing cost about US$250 or something. Chronograh is fun to use, Radar gun I don't know, I never try it.

Good Luck